Substrate penetrating through base island and packaging structure and packaging method thereof

Abstract

The invention provides a substrate penetrating through a base island, which ensures heat dissipation of a high-power product in subsequent packaging and reduces the cost. The substrate comprises a substrate body; the front surface of the base island is provided with an upper core area; an inner pin pad; an outer pin pad; the base island is arranged in the center area of the front face of the substrate body, the back face of the base island is a heat dissipation area, the front face and the back face of the base island are metal through areas, and the inner pin bonding pads are arranged on the positions, corresponding to the two side edges of the base island, of the front face of the substrate body. The outer pin bonding pad is arranged at the position, corresponding to the inner pin bonding pad, of the back face of the substrate body.

Description

Technical Field

[0001] This invention relates to the technical field of semiconductor packaging, specifically to a substrate with a through-island structure. The invention also provides a packaging structure and packaging method for the substrate. Background Technology

[0002] High-power semiconductor packaging technology is currently undergoing rapid iteration, primarily driven by the high-performance demands of fields such as new energy, electric vehicles, and AI computing. The widespread adoption of wide-bandgap semiconductor devices such as silicon carbide and gallium nitride has propelled innovation in packaging technology. In the future, high-power semiconductor packaging will evolve towards higher integration, more efficient heat dissipation, and standardization for cost reduction, further promoting its widespread application in new energy, AI, and electric vehicles.

[0003] To improve the heat dissipation performance and reliability of existing high-power packaged products, current technologies mostly employ metal frames (such as QFN / DFN) or traditional substrates (such as traditional BT substrates) for packaging. Metal frames, due to their high cost per layer of metal circuitry and molding process, are limited in terms of circuit complexity and diversity. While traditional substrates address these two issues, the conduction between the front and back sides of the substrate is mainly achieved through electroplating and via filling processes. This involves drilling holes in the substrate base layer and filling them with metal to achieve electrical conduction and heat dissipation between the upper and lower layers. However, its heat conduction capacity depends on the number and area of ​​the vias, resulting in limited heat dissipation capabilities. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a substrate with a through-island design, which ensures heat dissipation for high-power products during subsequent packaging and reduces costs.

[0005] A substrate penetrating a base island, characterized in that it comprises: substrate body; The base island has an upper core area on its front side; Internal pin pads; External pin pads; The central area on the front side of the substrate body is the base island, the back side of the base island is the heat dissipation area, the front and back sides of the base island are metal through areas, the inner pin pads are provided on the front side of the substrate body corresponding to the two sides of the base island, and the outer pin pads are located on the back side of the substrate body corresponding to the positions of the inner pin pads.

[0006] Its further features are: The base island is a through-type base island. The structure corresponding to the base island area is formed by electroplating a whole piece of metal to create an embedded substrate effect, thereby forming a through-type base island with a front base island and a back heat dissipation area. It electroplats the entire base island area, which runs through the entire substrate, connecting the core base island on the front of the substrate with the heat sink on the back, which greatly improves the heat dissipation efficiency of the product. At the same time, it simplifies the process flow, optimizes the electroplating, hot boiling softening, and film peeling processes in traditional QFN / DFN packaging, reduces process costs and process control difficulty, and improves product yield and reliability. The packaging units are distributed on the front side of the substrate.

[0007] A packaging mechanism for a substrate penetrating a base island, characterized in that it comprises: A substrate that extends through the base island includes a substrate body, a base island, an inner lead pad, and an outer lead pad. And the packaging unit, which includes a chip and metal bonding wires; The base island has an upper chip area on its front side, and the chip is disposed in the upper chip area of ​​the base island. The chip is electrically connected to the base island by high thermal conductivity silver paste. The chip is connected to the inner pin pad by metal bonding wires. The entire packaging unit is encapsulated by a plastic encapsulator.

[0008] Its further features are: The surface area of ​​the plastic encapsulation includes all parts of the front side of the substrate, including the chip, metal bonding wires, and internal lead pads. The high thermal conductivity silver paste is composed of nano silver powder, epoxy resin, and some antioxidants, diluents, coupling agents, and thixotropic agents. The metal bonding wire is made of copper wire, aluminum wire, palladium-plated copper wire, gold wire, silver wire, or silver alloy wire. The encapsulation body is a thermosetting encapsulation material composed of epoxy resin, curing agent, filler and additives, which is molded under high temperature and high pressure to protect the chip.

[0009] A packaging method based on a substrate with a through-island, characterized by comprising the following steps: S1. A substrate, a chip, and a molding die are provided, wherein the packaging units are arrayed on the substrate, and the molding die is matched with the packaging units; S2. Perform chip mounting, tightly bonding the chip to the chip mounting area on the base island using silver paste; S3. Perform wire bonding by tightly bonding the chip to the inner pin pads with metal bonding wires to achieve electrical connection between the chip and the substrate. S4. Molding: Molding the molding material onto the substrate through a molding mold to form a molding body, and then sealing the encapsulation unit into the molding body by hot pressing. S5. After completing the plastic sealing, cut the sealed product.

[0010] Its further feature is that, Step S2 is operated as follows: The substrate is placed in the loading area of ​​the mounting machine. The automatic loading system of the mounting machine will transfer the substrate to the processing area according to the preset program. Then, the dispensing head will apply silver paste to the mounting area of ​​the base island according to the preset program. After the dispensing is completed, the mounting equipment will use a bakelite nozzle to remove the chip from the substrate blue film by vacuum adsorption according to the preset program and place it on the silver paste. The chip position is controlled within ±50um and the angle is controlled within ±3°. After the chip is placed, it is pressed down according to the preset program to squeeze some silver paste from the periphery of the chip, so as to achieve a tight bond between the chip and the silver paste. After completion, the mounting machine will return the substrate to the unloading area of ​​the mounting machine and transfer it to the oven for high-temperature curing of the silver paste, so that the silver paste and the chip and the base island will undergo a cross-linking reaction, and the chip and the base island will be tightly connected.

[0011] Step S3 is operated as follows: After the substrate is cored, surface pretreatment is performed. Plasma cleaning is used to remove oxides and contaminants formed during the curing process to ensure the bonding surface is clean. Then, the substrate is transferred to the wire bonding machine. The automatic feeding system of the wire bonding machine will transfer the substrate to the processing area according to the preset program. Thermo-ultrasonic bonding or ultrasonic bonding technology is used. At a temperature of 150-250°C, ultrasonic waves with a frequency of 60-1101kHz and a pressure of 50-150gf are used to make the metal bonding wires and the pads undergo atomic diffusion to form a metallurgical bond. After the first solder point is completed, the wire feeding mechanism and motion control form a wire arc. The second solder point is then completed using the same process. After all the wire bonding is completed in the same way, the wire bonding machine will return the wire bonded products to the wire bonding machine unloading area according to the preset program.

[0012] The specific operation of step S4 is as follows: First, the substrate with the core and wire bonding completed is pre-baked to remove moisture and activate the adhesive. The molding compound is then molded into a molding body using a molding die. The encapsulation unit is then encapsulated within the pre-molded body by hot pressing. Subsequently, post-curing is performed. The molded product is then removed and transferred to an oven for heat treatment at 175°C for 8–12 hours to eliminate internal stress and increase crosslinking density.

[0013] This invention employs a unique through-type base island substrate. By optimizing the structural design of the substrate's heat-conducting area, it significantly improves heat dissipation efficiency. Depending on the product's base island range, it can effectively reduce thermal resistance by 30%-80%. At the same time, it optimizes the process flow, reducing the number of hot-boiling softening, electroplating, and film-removing process stations compared to other metal frame single-sided packages with similar high heat dissipation capabilities (such as QFN / DFN). This design not only reduces reliance on independent heat dissipation modules, lowering overall costs by 15%-25%, but also enhances reliability and lifespan through an integrated structure. It is suitable for the thermal management needs of various high-power devices, combining performance improvement with manufacturing economy. Attached Figure Description

[0014] Figure 1 This is a front view of the substrate of the present invention; Figure 2 This is a schematic diagram of the back side of the substrate of the present invention; Figure 3 This is a cross-sectional view of the substrate of the present invention; Figure 4 This is a front view of the finished product obtained using the substrate, packaging structure, and packaging method of the present invention; Figure 5 for Figure 4 Side view; Figure 6 for Figure 4 Rear view; The names corresponding to the serial numbers in the diagram are as follows: The substrate body 100 and the base island 101; 1. Upper core area, 2. Inner pin pad, 3. Heat dissipation area, 4. Outer pin pad, 5. Front copper layer, 6. Electroplated plug hole, 7. Metal through area, 8. Back copper layer, 9. Molded body, 10. Heat dissipation area. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is intended merely to illustrate selected embodiments of this application and is not intended to limit the scope of protection claimed by this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0016] It should be understood that in the description of embodiments of the present invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of the stated features.

[0017] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for mutual communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0018] A substrate that penetrates the base island, see Figure 1 It includes: a substrate body 100, a base island 101, an inner lead pad 2, and an outer lead pad 4; The front side of the base island 101 is provided with an upper core area 1; the center area of ​​the front side of the substrate body 100 is the base island 101, the back side of the base island 101 is a heat dissipation area 3, the front and back sides of the base island 101 are metal through areas, the front side of the substrate body 100 is provided with inner pin pads 2 corresponding to the two sides of the base island 101, and the back side of the substrate body 100 is provided with outer pin pads 4 corresponding to the inner pin pads 2.

[0019] In specific implementation, the base island 101 is a through-type base island. The area corresponding to the base island 101 is electroplated and formed as a whole, so that the front base island 101 and the heat dissipation area 3 on the back of the electroplated and formed structure are connected. The base island area is electroplated and formed as a whole, which runs through the entire substrate and connects the core area 1 on the front of the substrate with the heat dissipation area 3 on the back. This greatly improves the heat dissipation efficiency of the product. At the same time, it simplifies the process flow, optimizes the electroplating, hot boiling softening, and film peeling processes in traditional QFN / DFN packaging, reduces process costs and process control difficulty, and improves product yield and reliability.

[0020] In specific implementation, the substrate body 100 is made of BT material, see... Figure 3 Its base island 101 is a metal through area 7 located in the center. The surface area of ​​the inner pin pad 2 is printed with a front copper layer 5, and the surface area of ​​the outer pin pad 4 is printed with a back copper layer 8. The inner pin pad 2 and the outer pin pad 4 are electrically connected through the metal in the electroplated plug hole 6.

[0021] A packaging mechanism for a substrate that penetrates the base island, see Figures 1-6It includes: The substrate that runs through the base island includes a substrate body 100, a base island 101, an inner lead pad 2, and an outer lead pad 4. And the packaging unit, which includes a chip and metal bonding wires; The front side of the base island 101 has an upper chip area 1, on which the chip is located. The chip is electrically connected to the base island 101 via high thermal conductivity silver paste. The chip is connected to the inner pin pad 2 via metal bonding wire. The entire packaging unit is encapsulated by a plastic encapsulator 9.

[0022] The surface area of ​​the plastic package 9 includes all parts of the front side of the substrate, including the chip, metal bonding wire, and internal lead pads 2; The high thermal conductivity silver paste is composed of nano silver powder, epoxy resin, and some antioxidants, diluents, coupling agents, and thixotropic agents. The metal bonding wire is made of copper wire, aluminum wire, palladium-plated copper wire, gold wire, silver wire, or silver alloy wire.

[0023] The molding compound 9 is a thermosetting encapsulation material composed of epoxy resin, curing agent, filler and additives. It protects the chip by high temperature and high pressure molding. The heat dissipation area 3 on the back of the substrate body 100 extends to the periphery to form an overall heat dissipation area 10.

[0024] A packaging method based on a substrate with a through-island structure includes the following steps: S1. Provides a substrate, a chip, and a molding die. Packaging units are arrayed on the substrate, and the molding die matches the packaging units. S2. Perform chip mounting, tightly bonding the chip to the chip mounting area on the base island using silver paste; The specific operation is as follows: The substrate is placed in the feeding area of ​​the mounting machine. The automatic feeding system of the mounting machine will transfer the substrate to the processing area according to the preset program. Then, the dispensing head will apply silver paste to the mounting area of ​​the base island according to the preset program. After the dispensing is completed, the mounting equipment will use a bakelite nozzle to remove the chip from the substrate blue film by vacuum adsorption according to the preset program and place it on the silver paste. The chip position is controlled within ±50um and the angle is controlled within ±3°. After the chip is placed, the pressure is pressed down according to the preset program to squeeze some silver paste from the edges of the chip, so as to achieve a tight bond between the chip and the silver paste. After completion, the mounting machine will return the substrate to the unloading area of ​​the mounting machine and transfer it to the oven for high-temperature curing of the silver paste, so that the silver paste and the chip and the base island will undergo a cross-linking reaction, and the chip and the base island will be tightly connected. S3. Perform wire bonding, using metal bonding wires to tightly bond with the internal lead pads to achieve electrical connection between the chip and the substrate. The specific operation is as follows: After the substrate is cored, surface pretreatment is performed. Plasma cleaning is used to remove oxides and contaminants formed during the curing process to ensure the bonding surface is clean. Then the substrate is transferred to the wire bonding machine. The automatic feeding system of the wire bonding machine will transfer the substrate to the processing area according to the preset program. Thermo-ultrasonic bonding or ultrasonic bonding technology is used. At a temperature of 150-250°C, ultrasonic waves with a frequency of 60-1101kHz and a pressure of 50-150gf are used to make the metal bonding wires and the pads undergo atomic diffusion to form a metallurgical bond. After the first solder point is completed, the wire feeding mechanism and motion control form a wire arc. The second solder point is then completed using the same process. After all the wire bonding is completed in the same way, the wire bonding machine will return the wire bonded products to the wire bonding machine unloading area according to the preset program. S4. Molding: Molding material is molded onto the substrate through a molding mold to form a molding body. The packaging unit is then encapsulated in the molding body by thermoforming. The specific operation is as follows: First, the substrate with the core and wire bonding completed is pre-baked to remove moisture and activate the adhesive. The molding compound is then molded into a molding body through a molding mold. The packaging unit is then encapsulated in the pre-molded body by hot pressing. Subsequently, post-curing is performed. The molded product is then removed and transferred to an oven for heat treatment at 175°C for 8–12 hours to eliminate internal stress and increase cross-linking density. S5. After completing the plastic sealing, cut the sealed product.

[0025] This invention employs a unique through-type base island substrate. By optimizing the structural design of the substrate's heat-conducting area, it significantly improves heat dissipation efficiency. Depending on the product's base island range, it can effectively reduce thermal resistance by 30%-80%. At the same time, it optimizes the process flow, reducing the number of hot-boiling softening, electroplating, and film-removing process stations compared to other metal frame single-sided packages with similar high heat dissipation capabilities (such as QFN / DFN). This design not only reduces reliance on independent heat dissipation modules, lowering overall costs by 15%-25%, but also enhances reliability and lifespan through an integrated structure. It is suitable for the thermal management needs of various high-power devices, combining performance improvement with manufacturing economy.

Claims

1. A substrate through base island, characterized by, It comprises: a substrate body; a base island, the front surface of which is provided with an upper core area; an inner pin pad; an outer pin pad; the central area of the front surface of the substrate body is the base island, the back surface of the base island is a heat dissipation area, the front and back surfaces of the base island are metal through areas, and the front surface of the substrate body is provided with the inner pin pad corresponding to the two side edges of the base island, and the back surface of the substrate body is the outer pin pad corresponding to the position of the inner pin pad.

2. The substrate through base island of claim 1, wherein: The base island is a through base island, and the structure corresponding to the base island surface area is that the whole metal is formed into an embedded substrate effect by electroplating, thereby forming a through base island with a front base island and a back heat dissipation area.

3. The substrate through via base island of claim 2, wherein: The packaging units are distributed on the front surface of the substrate.

4. A packaging mechanism of a substrate through a base island, characterized by, It comprises: a through base island substrate according to any one of claims 1-3, comprising a substrate body, a base island, an inner pin pad, and an outer pin pad; and a packaging unit comprising a chip and a metal bonding wire; the front surface of the base island is provided with an upper core area, the chip is arranged on the upper core area of the base island, the chip is electrically connected to the base island through high-thermal-conductivity silver glue, the chip is connected to the inner pin pad through the metal bonding wire, and the packaging unit as a whole is encapsulated by a plastic encapsulation body.

5. The through via substrate packaging mechanism according to claim 4, wherein: The surface area of the plastic encapsulation body encapsulation includes all parts of the front surface of the substrate, including the chip, the metal bonding wire, and the inner pin pad.

6. The through via substrate packaging mechanism according to claim 4, wherein: The high-thermal-conductivity silver glue is composed of nano-silver powder, epoxy resin, and part of antioxidant, diluent, coupling agent, and thixotropic agent.

7. The through via substrate on island packaging mechanism of claim 4, wherein: The metal bonding wire is made of copper wire, aluminum wire, palladium-plated copper wire, gold wire, silver wire, or silver alloy wire.

8. The through via substrate on island packaging mechanism of claim 4, wherein: The plastic encapsulation body is a thermosetting encapsulation material composed of epoxy resin, curing agent, filler, and additive, which protects the chip by high-temperature and high-pressure forming.

9. A packaging method based on the through-island substrate according to any one of claims 1 to 3, characterized by, It comprises the following steps: S1, providing a substrate, a chip, and a plastic encapsulation mold, the substrate is arrayed with the packaging units, and the plastic encapsulation mold matches the packaging units; S2, performing core loading, the chip is tightly combined with the core area of the base island through silver glue; S3, performing wire bonding, the metal bonding wire is tightly welded with the inner pin pad to realize the electrical connection between the chip and the substrate; S4, plastic encapsulation, the plastic encapsulation material is plastic encapsulated on the substrate through the plastic encapsulation mold to form a plastic encapsulation body, and the packaging units are encapsulated in the plastic encapsulation body through hot pressing; S5, cutting the plastic encapsulation product after the plastic encapsulation is completed.

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